Add translation from internal kw to ones in tick_params()

Author: stefmolin

lib/matplotlib/axes/_base.py

@@ -3327,7 +3327,7 @@ def tick_params(self, axis='both', **kwargs):
 
         Tick properties that are not explicitly set using the keyword
         arguments remain unchanged unless *reset* is True. For the current
-        style defaults, see :meth:`matplotlib.axis.Axis.get_tick_params`.
+        style defaults, see `.Axis.get_tick_params`.
 
         Parameters
         ----------

lib/matplotlib/axis.py

@@ -943,7 +943,7 @@ def set_tick_params(self, which='major', reset=False, **kwargs):
 
         See Also
         --------
-        :meth:`.Axis.get_tick_params`
+        .Axis.get_tick_params
             View the current style defaults for ticks, ticklabels, and
             gridlines.
         """
@@ -988,6 +988,10 @@ def get_tick_params(self, which='major'):
         which : {'major', 'minor'}, default: 'major'
             The group of ticks to which the parameters are applied.
 
+        Returns
+        -------
+        dict on properties that deviate from the default
+
         Notes
         -----
         This method returns the default values for styling *new* elements
@@ -998,11 +1002,13 @@ def get_tick_params(self, which='major'):
         """
         _api.check_in_list(['major', 'minor'], which=which)
         if which == 'major':
-            return self._major_tick_kw
-        return self._minor_tick_kw
+            return self._translate_tick_params(
+                self._major_tick_kw, reverse=True
+            )
+        return self._translate_tick_params(self._minor_tick_kw, reverse=True)
 
     @staticmethod
-    def _translate_tick_params(kw):
+    def _translate_tick_params(kw, reverse=False):
         """
         Translate the kwargs supported by `.Axis.set_tick_params` to kwargs
         supported by `.Tick._apply_params`.
@@ -1013,9 +1019,12 @@ def _translate_tick_params(kw):
 
         Returns a new dict of translated kwargs.
 
-        Note: The input *kwargs* are currently modified, but that's ok for
-        the only caller.
+        Note: Use reverse=True to translate from those supported by
+        `.Tick._apply_params` back to those supported by
+        `.Axis.set_tick_params`.
         """
+        kw_ = {**kw}
+
         # The following lists may be moved to a more accessible location.
         allowed_keys = [
             'size', 'width', 'color', 'tickdir', 'pad',
@@ -1040,19 +1049,27 @@ def _translate_tick_params(kw):
             'labelright': 'label2On',
             'labeltop': 'label2On',
         }
-        kwtrans = {newkey: kw.pop(oldkey)
-                   for oldkey, newkey in keymap.items() if oldkey in kw}
-        if 'colors' in kw:
-            c = kw.pop('colors')
+        if reverse:
+            kwtrans = {
+                oldkey: kw_.pop(newkey)
+                for oldkey, newkey in keymap.items() if newkey in kw_
+            }
+        else:
+            kwtrans = {
+                newkey: kw_.pop(oldkey)
+                for oldkey, newkey in keymap.items() if oldkey in kw_
+            }
+        if 'colors' in kw_:
+            c = kw_.pop('colors')
             kwtrans['color'] = c
             kwtrans['labelcolor'] = c
         # Maybe move the checking up to the caller of this method.
-        for key in kw:
+        for key in kw_:
             if key not in allowed_keys:
                 raise ValueError(
                     "keyword %s is not recognized; valid keywords are %s"
                     % (key, allowed_keys))
-        kwtrans.update(kw)
+        kwtrans.update(kw_)
         return kwtrans
 
     def set_clip_path(self, clippath, transform=None):

lib/matplotlib/tests/test_axes.py

@@ -6379,19 +6379,28 @@ def test_tick_apply_tickdir_deprecation():
 
 def test_axis_get_tick_params():
     axis = plt.subplot().yaxis
-    initial_major_style = {**axis.get_tick_params(which='major')}
-    initial_minor_style = {**axis.get_tick_params(which='minor')}
+    initial_major_style_translated = {**axis.get_tick_params(which='major')}
+    initial_minor_style_translated = {**axis.get_tick_params(which='minor')}
 
-    assert axis._major_tick_kw == initial_major_style
-    assert axis._minor_tick_kw == initial_minor_style
+    translated_major_kw = axis._translate_tick_params(
+        axis._major_tick_kw, reverse=True
+    )
+    translated_minor_kw = axis._translate_tick_params(
+        axis._minor_tick_kw, reverse=True
+    )
+
+    assert translated_major_kw == initial_major_style_translated
+    assert translated_minor_kw == initial_minor_style_translated
     axis.set_tick_params(labelsize=30, labelcolor='red',
                          direction='out', which='both')
 
-    new_major_style = {**axis.get_tick_params(which='major')}
-    new_minor_style = {**axis.get_tick_params(which='minor')}
-    assert initial_major_style != new_major_style
+    new_major_style_translated = {**axis.get_tick_params(which='major')}
+    new_minor_style_translated = {**axis.get_tick_params(which='minor')}
+    new_major_style = axis._translate_tick_params(new_major_style_translated)
+    new_minor_style = axis._translate_tick_params(new_minor_style_translated)
+    assert initial_major_style_translated != new_major_style_translated
     assert axis._major_tick_kw == new_major_style
-    assert initial_minor_style != new_minor_style
+    assert initial_minor_style_translated != new_minor_style_translated
     assert axis._minor_tick_kw == new_minor_style